Alien Invasions

Mapping movements of alien bird species.

- Albert Froneman

For the first time a global map of alien bird species has been produced, led by a team of researchers from University College London. It shows that human activities are the main determinant of how many alien bird species live in an area, but that alien species are most successful in areas already rich in native bird species.

‘One of the main ways humans are altering the world is by moving species to new areas where they do not normally occur. Our work shows why humans have been moving these “alien” bird species around for the past 500 years primarily through colonialism and the increasingly popular cage-bird trade and why some areas end up with more species than others,’ explained supervising author Professor Tim Blackburn.

For the study, the researchers collected and analysed data on the movement of almost 1000 alien bird species between the years 1500 and 2000. This was used to create a new open-access database that was then analysed for patterns in the context of historical events and natural environmental variation.